dspl/filter__freq__resp_8c_source.html

/*

* Copyright (c) 2015-2024 Sergey Bakhurin

* Digital Signal Processing Library [http://dsplib.org]

*

* This file is part of libdspl-2.0.

*

* is free software: you can redistribute it and/or modify

* it under the terms of the GNU Lesser    General Public License as published by

* the Free Software Foundation, either version 3 of the License, or

* (at your option) any later version.

*

* DSPL is distributed in the hope that it will be useful,

* but WITHOUT ANY WARRANTY; without even the implied warranty of

* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.    See the

* GNU General Public License for more details.

*

* You should have received a copy of the GNU Lesser General Public License

* along with Foobar.    If not, see <http://www.gnu.org/licenses/>.

*/


#include <stdlib.h>

#include <string.h>

#include <math.h>

#include "dspl.h"


#ifdef DOXYGEN_ENGLISH


#endif

#ifdef DOXYGEN_RUSSIAN


#endif

int DSPL_API filter_freq_resp(double* b, double* a, int ord,

                              double* w, int n, int flag,

                              double* mag, double* phi, double* tau)

{

    int res, k, flag_analog;


    complex_t *hc  = NULL;

    double *phi0   = NULL;

    double *phi1   = NULL;

    double *w0     = NULL;

    double *w1     = NULL;


    if(!b || !w)

        return ERROR_PTR;

    if(ord < 1)

        return ERROR_FILTER_ORD;

    if(n < 1)

        return ERROR_SIZE;


    flag_analog = flag & DSPL_FLAG_ANALOG;


    hc = (complex_t*) malloc (n*sizeof(complex_t));


    res = flag_analog ?

          freqs(b, a, ord, w, n, hc) :

          freqz(b, a, ord, w, n, hc);


    if(res != RES_OK)

        goto exit_label;


    if(mag)

    {

        if(flag & DSPL_FLAG_LOGMAG)

        {

            for(k = 0; k < n; k++)

                mag[k] = 10.0 * log10(ABSSQR(hc[k]));

        }

        else

        {

            for(k = 0; k < n; k++)

                mag[k] = sqrt(ABSSQR(hc[k]));

        }

    }


    if(phi)

    {

        for(k = 0; k < n; k++)

            phi[k] = atan2(IM(hc[k]), RE(hc[k]));


        if(flag & DSPL_FLAG_UNWRAP)

        {

            res = unwrap(phi, n, M_2PI, 0.8);

            if(res != RES_OK)

                goto exit_label;

        }

    }


    if(tau)

        res = group_delay(b, a, ord, flag, w, n, tau);


exit_label:

    if(hc)

        free(hc);

    if(phi0)

        free(phi0);

    if(phi1)

        free(phi1);

    if(w0)

        free(w0);

    if(w1)

        free(w1);

    return res;

}